FORT DRUM  The posts 3rd Brigade Combat Team formally signified the start of a nine-month deployment to Afghanistan in what may be its final overseas mission.

Col. Samuel E. Whitehurst, the brigades commander, told the hundreds of soldiers lining Sexton Field on Monday morning that they were ready for their mission, advising Afghan police and military forces across multiple areas in the eastern side of the country.

We face an enemy that is committed to our failure and the failure of the Afghan security forces, he said. But our enemy faces a brigade combat team that has prepared for this mission for the last 14 months. They face a brigade whose own history is tied to Afghanistan, both in Kandahar, the birthplace of the Taliban, and in the mountains of eastern Afghanistan, where some of the toughest fighting in this war has occurred.

Among the goals for their time in country is helping the country ready for its presidential elections next spring, and helping to withdraw equipment and turn over installations to Afghan forces in line with the conclusion of major military activity at the end of 2014.

Im not going to sugar-coat this, said Maj. Gen. Stephen J. Townsend, Fort Drum and 10th Mountain Division commander. The mission you have is extremely challenging  in fact, arguably the most challenging and demanding mission you have undertaken in this war thus far.

The role of the brigade is similar to that assumed by the 10th Mountain Divisions 1st, 2nd and 4th Brigade Combat Teams.

Col. Whitehurst said the brigade has readied for its mission with exercises both locally and at the Joint Readiness Training Center at Fort Polk, La., covering all levels of its leadership.

The first group of about 160 left early Monday, before the ceremony. The rest of the approximately 2,000 soldiers deploying for the mission will be leaving within the next two months. The deployment is the fourth to Afghanistan for the brigade since its formation in 2004, following deployments in 2006, 2009 and 2011.

The deployment comes after the brigade was selected in June for inactivation at some point between now and the fiscal year 2017. No additional guidance has been provided since the initial announcement. After the ceremony, Col. Whitehurst said he received his introduction last week to what would have to be done for its inactivation.

During his remarks, Gen. Townsend praised the work of the brigade, nicknamed the Spartans, since its activation during a time of rapid Army expansion.

The Spartans have since answered our nations call, both at home and abroad, he said.

Gen. Townsend pointed out that the brigade has produced highly decorated soldiers such as Sgt. 1st Class Jared C. Monti, who was posthumously awarded the Medal of Honor in September 2009 for his actions in Afghanistan in June 2006.

It is their experience earned during this war that causes our Army to continue to call on these soldiers, Gen. Townsend said.

Last week, it was announced a soldier with ties to the brigade, Capt. William D. Swenson, will receive the Medal of Honor in October, becoming the first living Army officer to be nominated for the award in four decades.

Gen. Townsend delayed his remarks to allow an emissary of Gov. Andrew M. Cuomo to read a statement thanking and supporting the brigade for its upcoming mission.

Also in attendance were Rep. William L. Owens, D-Plattsburgh; F. Anthony Keating, civilian aide to the secretary of the Army; and hundreds of family members of brigade soldiers.